Used Universal Audio 4-710d Mic Pre-Amp Universal Audio Preamp/DI This Universal Audio 4-710d four channel mic preamp is the perfect choice if you are looking to add some extra tone to your recording! It's in excellent condition with only minor scratches. Otherwise, it works great!By merging the best of UA’s classic analog design with smart modern features and workflow enhancements, the 4-710d is the most flexible microphone preamp in the UA lineup.Featuring four high-end mic/line preamps with a unique tube/solid-state tone blending circuit, as well as classic 1176-style compression on each mic channel, the 4-710d also offers tons of digital I/O to expand your setup.